1. Field of the Invention
The present invention relates generally to stiffening members used in constructing buildings to resist horizontal shear forces and, more particularly, to metal stiffening members used to reinforce roofs and floors of corrugated metal decking.
2. Description of the Related Art
Corrugated metal decking is used in the construction of large buildings, as part of a horizontal floor or roof structure. Such structures are generally referred to as diaphragms. In addition to serving as floors and roofs, diaphragms give the building resistance to horizontal shear forces, such as are caused by wind and earthquakes.
A corrugated deck consists of multiple deck panels. Each panel consists of repeating corrugations, where the corrugations extend parallel to the longitudinal axis of the deck panel. Deck panels are usually attached to each other at their side (longitudinal) edges by an overlapping joint known as a sidelap joint. Deck panels are also usually attached to each other at their ends in an overlapping fashion. Welds are typically used to attach deck panels to each other and to underlying horizontal support structures, such as wide-flange beams.
If subjected to a horizontal shear force of sufficient strength, a diaphragm will eventually buckle or compress. The ability of a diaphragm to resist horizontal shear forces depends on several factors, including the thickness of the deck, the size of the deck, the stiffness of the deck, and the way in which the deck is attached to the supporting structure. The stiffer the diaphragm, the greater the degree of shear resistence.
Several different types of stiffening members or shear resisting structures have been used to provide additional shear resistance to a diaphragm. U.S. Pat. No. 4,894,967 issued to Morton discloses a diaphragm including a fluted or corrugated deck and a shear resisting member. The fluted deck is supported by horizontal support beams. The shear resisting member is attached to the top of the fluted deck, perpendicular to the flutes of the deck. The shear resisting member has a horizontal portion that is welded to the tops of the flutes of the deck, using a fillet type of weld. The shear resisting member also has vertical tabs that extend downward into the troughs of the flutes of the deck and are welded to the troughs of the deck and through the troughs to the horizontal support beam, using an arc spot type of weld. Thus, the shear resisting member requires two different welds per flute or corrugation, necessitating different tools and different welding materials.
U.S. Pat. No. 4,186,535, 4,333,280, and 4,335,557, also issued to Morton, disclose a diaphragm including a fluted deck and a load translation member similar to that disclosed by U.S. Pat. No. 4,894,967. The load translation member may be Z-shaped or C-shaped or a profile plate member. The load translation member is welded to the open end of a fluted deck and therefore cannot be used with a cantilevered deck (i.e., a deck where the open end of the deck extends past the underlying wide-flange beam). The Z-shaped and C-shaped load translation members also cannot be used where the end of the deck abuts a vertical wall or where two deck panels are joined with their ends abutting (an interior butt joint). Although the profile plate member can be used where the deck abuts a vertical wall and on interior butt joints, it is not easy to install and requires considerable time and expense. The profile plate member also does not provide shear resistance to both deck panels in an interior butt joint.
Thus, the known stiffening members are unsatisfactory. Some cannot be used with a cantilevered deck. Those that can be used with a cantilevered deck are not satisfactory because they require two different types of welds per flute or corrugation, resulting in increased time, complexity, labor costs, and material costs. Other types of stiffening members cannot be used, or are more difficult and costly to use, where the deck abuts a vertical wall or in an interior butt joint. Thus, there is a need for a stiffening member that can be used with a cantilevered corrugated deck that can be installed in an efficient and cost-effective fashion. There is also a need for a stiffening member that can be used where a deck abuts a vertical wall and where an interior butt joint is used.
The stiffening member of the present invention is adapted to overcome the above-noted shortcomings and to fulfill the needs of providing a stiffening member that can be used with a cantilevered deck and is quick, easy, and cost-effective to install.
One aspect of the invention comprises a stiffening member for use in a diaphragm of a building. The stiffening member comprises a plurality of U-shaped portions with an outer surface, a plurality of horizontal, planar upper portions, an integral connection between one of the U-shaped portion""s side portions and an upper portion, and an integral connection between the other of the U-shaped portion""s side portions and another upper portion. Each U-shaped portion comprises first and second substantially vertical, planar side portions, a horizontal, planar floor portion, first and second corners integrally connecting the floor portion to the first and second side portions, respectively, and means for reinforcing one of the corners.
Another aspect of the invention includes a diaphragm of a building, comprising a horizontal structural member, a corrugated deck, the stiffening member described above, and means for attaching the stiffening member to the deck and to the horizontal structural member.
It is an object of the present invention to provide a stiffening member to be used in building diaphragms, including corrugated metal decking, to resist horizontal shear forces.
It is a further object of the invention to provide a stiffening member that can be used in cantilevered decks.
It is another object of the invention to provide a stiffening member that can be attached to corrugated metal decking in an easier, more cost-effective and less time-consuming fashion than existing shear resisting members.
It is yet another object of the invention to provide a stiffening member that can be attached to corrugated metal decking by a single weld per corrugation.
It is also an object of the invention to provide a stiffening member that can be attached to corrugated metal decking by a pin rather than a weld.
It is another object of the invention to provide a stiffening member that can be used where a deck abuts a vertical wall.
It is another object of the invention to provide a stiffening member that can be used in an interior butt joint.
It is also an object of the invention to provide a stiffening member that can be installed using the same type of welds that are used to construct corrugated decks.